Synthesis of highly ordered mesoporous hybrid silica from aromatic fluorinated organosilane precursors

Article abstract of DOI:10.1039/b206924p

Organo-fluorinated mesoporous MCM-41 type silica presenting a high degree of order has been prepared from co-condensation of tetraethoxysilane (TEOS) and pentafluorophenyltriethoxysilane [PFPTES (1)] in the presence of cetyltrimethylammonium bromide as a template. Both basic and acidic routes have been explored. In the presence of an excess of water using fluoro-precursor (1), most of the bound fluoro-organic moieties are cleaved, yielding to pentafluorophenyl doped silica. Higher fluorine content silica-based MCM-41 materials were obtained by using 2-pentafluorophenylethyltriethoxysilane [PFPETES (2)] as the organosilane precursor. In that case, the fluoro-containing groups remain covalently bound to the mesoporous inorganic network, yielding materials with potential hydrophobic, adsorbing and optical properties.

Full text of DOI:10.1039/b206924p

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Synthesis of highly ordered mesoporous hybrid silica from aromatic
fluorinated organosilane precursorsy
a
B e´ n e´ dicte Lebeau,* Claire Marichal, Alexia Mirjol, Galo J. de A. A. Soler-Illia,
a
b
b
c
c
d
Ralf Buestrich, Michael Popall, L e´ o Mazerolles and Cl e´ ment Sanchez*
b
a
Laboratoire de Mat e´ riaux Min e´ raux, CNRS UMR 7016, UHA, ENSCMu, 3 rue Alfred Werner,
8093, Mulhouse, France. E-mail: b.lebeau@univ-mulhouse.fr
6
b
Laboratoire de Chimie de la Mati e` re Condens e´ e, CNRS UMR 7574, Universit e´ P. et M. Curie,
place Jussieu, 75252, Paris cedex 05, France. E-mail: clems@ccr.jussieu.fr
4
c
Fraunhofer Institut f u¨ r Silicatforshung, W u¨ rsburg, Germany
Laboratoire Centre d’Etudes de Chimie M e´ tallurgique (CECM), CNRS UPR 2801,
d
1
5 rue G. Urbain, 94407, Vitry sur Seine, France
Received (in Montpellier, France) 11th July 2002, Accepted 16th September 2002
First published as an Advance Article on the web 10th December 2002
Organo-fluorinated mesoporous MCM-41 type silica presenting a high degree of order has been prepared from
co-condensation of tetraethoxysilane (TEOS) and pentafluorophenyltriethoxysilane [PFPTES (1)] in the
presence of cetyltrimethylammonium bromide as a template. Both basic and acidic routes have been explored.
In the presence of an excess of water using fluoro-precursor (1), most of the bound fluoro-organic moieties are
cleaved, yielding to pentafluorophenyl doped silica. Higher fluorine content silica-based MCM-41 materials
were obtained by using 2-pentafluorophenylethyltriethoxysilane [PFPETES (2)] as the organosilane precursor.
In that case, the fluoro-containing groups remain covalently bound to the mesoporous inorganic network,
yielding materials with potential hydrophobic, adsorbing and optical properties.
structure and properties can be reproducibly prepared. How-
Introduction
ever, to the best of our knowledge, practically no work has
been reported on periodically organised mesoporous organo-
fluorinated silicas. This is probably due to the difficulties in
compatibilising the self assembly of the template, the inorganic
and the fluorinated moieties, as well as the lack of fluoro-
organosilane availability. The present research describes the
first synthesis of ordered fluoro-organically modified meso-
porous silica.
There is currently extensive effort to develop methods for the
production of porous inorganic materials based on silica and
other oxides because of their potential for wide practical appli-
cations (catalysis, photonics, chromatography, specific mem-
branes, adsorbents, etc.). A key step in the synthesis of
porous materials continues to be the use of supramolecular
surfactant micellar or block copolymer templates for the inor-
1
ganic framework, resulting in mesoporous M41S phases. One
Fluoro-organically modified mesoporous silicas were first
synthesized under basic or acidic conditions from co-condensation
of tetraethoxysilane (TEOS) and pentafluorophenyltriethoxy-
silane (PFPTES, hereafter 1) or 2-pentafluorophenylethyl-
triethoxysilane (PFPETES, hereafter 2) in the presence of the
surfactant cetyltrimethylammonium bromide (C TMABr).
goal in structural control has been to provide new accessible
specific functions located in the internal pore surface. Chemi-
cal functionalisation of the inorganic framework of porous
materials, for example through the covalent coupling of an
organic moiety, is a promising approach to specific pore sur-
face properties such as hydrophobicity, polarity, and catalytic,
1
6
Final products were characterised by XRD, FTIR, chemical
2
–4
13
19
optical and electronic activity;
indeed, the tailoring of the
2
analysis, TGA–DTA, N adsorption–desorption, C, F and
2
9
pore surfaces presents direct interest in applications such as
catalysis, chromatography, controlled delivery or membranes.
Organo-functionalisation of ordered mesoporous silica-based
Si solid state MAS-NMR, and transmission electron
microscopy (TEM).
5
–9
solids can be achieved either by post-synthetic methods
via direct routes (one-pot synthesis).
or
The latter involves
1
0–17
Experimental
co-condensation of tetraalkoxysilanes and organotrialkoxy-
silanes in the presence of surfactants. The one-pot synthesis
method allows a higher organic content and a more homoge-
Synthesis of fluoro-organosilane precursors
1
8
Precursor 1 was synthesized by following the procedure
neous organic distribution in the material. Numerous studies
have pointed out the role and importance of the nature of the
2
0
described elsewhere (Fig. 1a). 24.7 g (100 mmol) pentafluoro-
bromobenzene (PFBB), 2.65 g (110 mmol) magnesium turn-
ings, 41.70 g (200 mmol) freshly distilled TEOS and a few
crystals of iodine were mixed together at room temperature
and diethyl ether was added drop-wise to the vigorously stirred
mixture until an exothermic reaction was observed (approx. 30
min). After stirring and refluxing for 16 h the mixture was
cooled to room temperature. An excess of n-heptane was
added to precipitate the magnesium salts. Filtration gave a
1
9
bonds comprising the hybrid inorganic–organic interface.
Hybrid materials with covalently bonded organic moieties
1
9
Class II hybrids ) can be readily designed by sol–gel chemi-
(
stry and thus a wide range of materials with tailor-made
y Electronic supplementary information (ESI) available: detailed
characterisation of sample C (TEOS/PFPETES 9/1). See http://
www.rsc.org/suppdata/nj/b2/b206924p/
1
66
New J. Chem., 2003, 27, 166–171
DOI: 10.1039/b206924p
This journal is # The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2003

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Table 1 Synthetic conditions for the fluorine-containing mesoporous
silica solids
a
Sample identification
Organosilane precursor
x
Catalyst
A1
A2
B1
B2
C
1
1
1
1
2
0.1
0.2
0.1
0.2
0.1
NaOH
NaOH
HCl
HCl
NaOH
a
Initial organosilane molar content.
Fig. 1 Reaction schemes for a) PFPTES (1) and b) PFPETES (2)
fluorinated precursors.
1
an MSL300 ( C at 75.4 MHz and Si at 59.6 MHz) and
3
29
1
9
DSX400 ( F at 376.5 MHz) Bruker spectrometers. Samples
were introduced into a 4 mm or 2.5 mm spinner and spun at
clear pale yellow solution. Solvents were removed and the resi-
1
due fractionally distilled under reduced pressure (18 Torr). H
13 29
kHz (for C and Si NMR acquisitions), 8 kHz and 15
4
kHz (for F NMR acquisitions). MAS Si NMR experiments
19
29
NMR (CDCl ) d: ꢀ1.28 (3H, OCH CH ); ꢀ3.96 (2H,
3
2
3
were made by using a 2 ms pulse (p/6) with a recycle delay of
1
9
OCH
ꢀ
2
CH
3
).
F NMR (CDCl
3
) d: ꢀ127.2 (2F, ortho);
13
0 s. CP-MAS C NMR experiments were run with a contact
6
151.0 (1F, para); ꢀ161.9 (2F, meta).
19
time of 1 ms and a recycle delay of 10 s. MAS F NMR spec-
tra were recorded with a 5.5 ms pulse (p/2) and a recycle
delay of 60 s. Tetramethylsilane was used as external chemical
Precursor 2 was synthesised by coupling a pentafluorostyr-
ene (PFS) group to triethoxysilane (TES) via a hydrosilylation
reaction (Fig. 1b). Platinum-1,3-divinyltetramethyldisiloxane
(
1
13
29
shift reference for H, C and Si NMR experiments. CFCl
3
Pt(DVS), 0.24% Pt, solution in xylene, ABCR, Karlsruhe)
19
was used as external chemical shift reference for F NMR
experiments.
2
1
was used as catalyst for the hydrosilylation reaction. 56
mmol (9.19 g) of TES in 20 ml of dry toluene were introduced
first into a three-necked round-bottomed flask under argon
X-Ray diffraction (XRD). XRD patterns were recorded on a
powder PW 1130 Philips diffractometer using Cu Ka radiation
ꢁ
atmosphere and cooled to 0 C with an ice bath. 56 mmol
(
10.88 g) of PFS in 20 ml of dry toluene were added under stir-
˚
(
l ¼ 1.5406 A).
ring to the TES solution. 0.784 mmol (350 ml) of Pt(DVS) was
then added under stirring and the resulting mixture was heated
Porosimetry. N adsorption–desorption measurements were
2
performed on an ASAP 2010 Micromeritics equipment.
ꢁ
at reflux (110 C) for 50 h. Most of the platinum colloids were
removed by centrifugation (20 000 rpm for 20 min). Toluene
was then removed by evaporation under vacuum; this opera-
tion was repeated to ensure complete elimination of volatile
Fourier transform infra-red (FTIR). FTIR transmission spec-
tra were recorded on pressed KBr pellets on a Nicolet Magna-
IR 550 spectrophotometer.
unreacted starting products (checked by NMR). A transparent
1
yellowish liquid was finally obtained. H NMR (CDCl ) d: 0.9
3
(
t, (CH
3 2 3 2 2 6 5 3 2
CH O) Si–CH CH –C F ); 1.2 (t, CH CH O); 2.7 (t,
Chemical analyses. Fluorine loadings in final products were
measured using elemental analysis at the Service Central des
Analyses, CNRS, Vernaison, France.
1
9
(
NMR (CDCl
ꢀ
CH CH O) Si–CH CH –C F ); 3.85 (q, CH CH O).
5
F
3
2
3
2
2
6
3
2
3
) d: ꢀ148.4 (2F, ortho), ꢀ160.7 (1F, para);
165.0 (2F, meta).
Transmission electron microscopy (TEM). TEM observations
were made using a TOPCON 002B microscope operating at
Preparation of fluorine-containing mesoporous silica solids
2
00 kV. Samples were observed either directly after deposition
The samples were synthesized from either an alkaline or an
acidic mixture containing one of the following molar composi-
tions: 0.12 C TMABr:0.50 NaOH:1 ꢀ x TEOS:x 1 (or 2):130
of powder on a copper grid or as ultramicrotomed slices after
embedding in an epoxy resin.
1
6
H
2
O or 0.12 C16TMABr:9.2 HCl:1 ꢀ x TEOS:x 1:130 H
2
O
(
x ¼ 0.1 or 0.2). In a typical preparation under alkaline condi-
Results and discussion
tions, 0.80 g of C16TMABr (Aldrich) was dissolved in 42.8 ml
of 0.1 M NaOH. The appropriate amounts of TEOS (Aldrich)
and 1 (or 2) were added, and the mixture was stirred for 24 h at
Ordered mesoporous silica modified with PFPTES (precursor 1)
XRD patterns obtained from surfactant-extracted samples
prepared under alkaline conditions (A1 and A2) showed four
room temperature. The solid product was filtered, washed with
ꢁ
H
2
O and dried for 24 h in an oven at 60 C. Extraction of the
broad Bragg reflections that can be indexed as d100 , d110
,
surfactant was performed by stirring a suspension of the solid
ꢀ
3
product (1 g) in 1.0 mol dm HCl in EtOH (25 ml of HCl 37%
d
200 and d210 (see Fig. 2 and Table 2) and are characteristic
ꢁ
of a hexagonal symmetry. The presence of these four diffrac-
tion peaks indicated that both samples A1 and A2 have
MCM-41 type architecture with long range order. Two
broader Bragg reflections were observed on the XRD pattern
of sample B2, which can be indexed as d100 and d110 . These
two diffraction peaks are consistent with a hexagonal symme-
try but with a low degree of organisation. Concerning sample
B1, the XRD pattern displayed only one broad Bragg diffrac-
tion that indicates a disordered worm-like mesostructure, as in
(
2
Prolabo) mixed with 300 ml of absolute EtOH) at 70 C for
4 h. The surfactant-extracted material was filtered, washed
ꢁ
with EtOH and dried for 24 h at 60 C. For preparations under
acidic conditions, the same general preparation was used,
except that the 0.1 M NaOH aqueous solution was replaced
by a 3.85 M HCl aqueous solution. The synthetic details of
the different samples prepared are summarised in Table 1.
Characterisation
2
2
the case of HMS materials.
1
19
Nuclear magnetic resonance (NMR). H and F NMR spec-
tra of fluoro-organosilane precursors 1 and 2 were obtained in
CDCl as solvent using a Bruker WM 400 and a Bruker AC
Acidic conditions lead to less ordered mesostructured silica
materials than alkaline conditions. Three main processes,
which are known to be different in acid or alkaline media,
can be held responsible for such observed differences: a) the
3
2
50, respectively. Solid state NMR experiments were run on
New J. Chem., 2003, 27, 166–171
167

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about 950 m g ). Samples prepared under alkaline condi-
tions present higher average pore diameters (28.8 and 29.5
2
ꢀ1
(
˚
A) than samples made under acidic conditions (22.7 and 22.2
˚
A). Taking into account the XRD data, the materials prepared
˚
via the basic route present a wall thickness of about 20 A, com-
˚
pared with about 10 A for the materials prepared from an
acidic route. From these results, it seems that both wall thick-
ness and pore diameter explain the higher d-spacings observed
for samples made from a basic route. Micelle size (and there-
fore, the cavity size) should also be related to the characteris-
2
5
tics of the medium (pH, ionic force, counterions, etc.).
FTIR spectra recorded on as-synthesised samples showed
ꢀ
1
clearly three groups of bands: shoulders at 1410–1450 cm
,
a doublet at 1506–1523 cm and a broad band at 1620–
ꢀ
1
ꢀ
1
1
650 cm ; all these bands are characteristic of aromatic
ring vibration and aromatic C=C stretching bands,
respectively. C–F stretching frequencies (bands at 1076, 1131
n
C C
=
ꢀ1
and 1152 cm ) are overlapped by the Si–O stretching modes
(
Fig. 2 XRD pattern of the surfactant extracted sample A2.
ꢀ
1 26
950–1200 cm ). Vibrations indicative of the surfactant at
ꢀ
1
2
850–2950 cm
were also observed. However, the bands
2
3
nature of the surfactant (S)/inorganic (I) interfaces, b) the
kinetics of hydrolysis/co-condensation of TEOS and the
fluorinated precursors, c) the kinetics of the cleavage of
due to C=C bonds as well as the bands characteristic of the
surfactant were not detectable in the spectra of the surfac-
2
4
13
tant-extracted samples. A C MAS NMR study confirmed
ꢀ
+
the organofluoro-moieties (vide infra). An electrostatic I S
synthetic path was identified for the basic route whereas an
the absence of pentafluorophenyl groups and surfactant mole-
cules in the final materials.
+
ꢀ
+
electrostatic I X S synthetic path (X ¼ Cl) was identified
F/Si molar ratios in final materials, calculated from chemi-
cal analyses, are reported in Table 2. In all cases final F/Si
molar ratios are much lower than initial F/Si molar ratios
and indicate the incorporation of 0.6 and about 8% of fluori-
nated groups for surfactant-extracted materials made under
acidic and basic conditions, respectively. Final F/Si molar
ratios of 0.02 and 0.1 were measured in as-synthesised high
nominal fluorine ratio samples B2 and A2, respectively. These
results indicate that a great part of the fluorine component has
been lost during the formation of the first hybrid mesophase.
Three resonance lines at ꢀ129.6, ꢀ150.7 and ꢀ164.7 ppm
for the acid route. In the latter case, the interaction I/S is more
‘‘fuzzy’’, which should lead to a less ordered mesostructure.
Indeed, it has been observed that basic synthesis conditions
2
5
lead to better ordered organosilicas. High ionic strength is
also probably responsible for the improved organisation of
surfactant aggregates and, thus, for the high degree of organi-
sation of the hybrid mesostructured complex that forms in the
basic medium. Values of d100-spacing obtained from XRD pat-
terns are higher for samples prepared under alkaline condi-
˚
tions (48.8 and 46.5 A) than for samples made under acidic
˚
conditions (32.0 and 35.2 A). Such differences may be
19
were observed in the F MAS NMR spectrum of the as-
explained by a higher wall thickness for the samples obtained
from basic solutions (A1 and A2 samples, vide infra), a conse-
quence of the higher condensation degree reached in alkaline
media. TEM images of the A2 material (alkaline conditions)
showed hexagonal sets of lattice fringes, as well as parallel
fringes corresponding to side-on projections of the mesostruc-
ture (Fig. 3), which are consistent with the long range order
parameters determined by XRD.
synthesised high fluorine content sample made from a basic
mixture (Fig. 5). These resonances correspond to the three
types of fluorine nuclei from the pentafluorophenyl groups in
ortho, para and meta positions, respectively. After surfactant
extraction only the peak at ꢀ129.6 ppm is clearly observed
1
9
in the F MAS NMR spectrum. Resonances of fluorine nuclei
from the pentafluorophenyl group are not clearly observed in
1
9
the F MAS NMR spectra of the as-synthesised and surfac-
tant-extracted high fluorine content samples made from acidic
mixtures. The fluorine content of these latter materials is prob-
2
Type-IV N adsorption–desorption isotherms characteristic
of mesoporous solids were obtained for all surfactant-free sam-
ples. BET specific surface areas (SBET) and average BJH pore
diameters (ØBJH) are reported in Table 2. For samples A1 and
A2 a sharp condensation capillary step was observed (Fig. 4)
that indicates a small pore size distribution. Whatever the cat-
alyst used, the SBET values are high and similar. Slightly higher
1
9
ably too low to be detectable by F MAS NMR spectroscopy.
These results are in agreement with the chemical analysis data
and confirmed by Si MAS NMR experiments.
2
9
For all samples, the collected spectra displayed three reso-
nances at about ꢀ92, ꢀ101 and ꢀ110 ppm that correspond
S
BET values were measured for high initial F/Si molar ratio
2 3 4
to Q , Q and Q units, respectively (Fig. 6). In all cases the
2
ꢀ1
) than for low initial F/Si molar ratio
(
about 1050 m
g
resonances characteristic of Q3 and Q4 are predominant
Table 2 XRD [d-spacings and unit cell parameter (a ¼ 2d100 3)], N
BJH pore diameter (ØBJH) and chemical analysis data [F/Si initial (F/Si
mesoporous silica solids
/p
2
adsorption–desorption [BET specific surface area (SBET)] and adsorption
) and final (F/Si ) molar ratios] of surfactant extracted fluorine-containing
f
a
i
˚
XRD d-spacings and a/A
N
2
adsorption–desorption
Chemical analysis
2
ꢀ1
˚
a
Sample
d
100
d
110
d
200
d
210
a
S
BET/m g
Ø
BJH/A
F/Si
i
F/Si
f
A1
A2
B1
B2
C
48.8
46.5
32.0
35.2
37.1
28.1
26.8
—
24.4
23.2
—
18.8
17.6
—
56.3
53.7
37.0
40.6
43.3
940
1060
960
28.8
29.5
22.7
22.2
27.0
0.5
1.0
0.5
1.0
0.5
0.021
0.077
0.003
0.006
0.300
20.3
21.8
—
18.7
—
14.2
1020
1260
a
Initial F/Si molar ratio was determined from the experimental conditions.
1
68
New J. Chem., 2003, 27, 166–171

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1
9
Fig. 5
tant extracted (b) sample A2.
F MAS NMR spectrum of the as-synthesized (a) and surfac-
Fig. 3 TEM micrograph of the surfactant-extracted sample A2.
2
Type-IV isotherms are obtained by N adsorption–desorp-
tion measurements, which are characteristic of a high surface
2
ꢀ1
area mesoporous solid (1260 m g , see ESI). A sharp pore
size distribution was observed with an average BJH pore dia-
˚
meter of 27 A. Taking into account the d100 value measured
˚
by XRD, the pore wall thickness is about 10 A.
The FTIR spectra of as-synthesised samples C (Fig. 8)
clearly showed the same nC
A and B samples (groups at 1410–1456, 1490–1530 and
=
vibration bands present in the
C
ꢀ
1
1
620–1650 cm ). In addition, two nC–F vibration bands are
clearly observed in the as-synthesised spectrum (1120 and
ꢀ
1
1
cm
154 cm ). Surfactant bands (nC–H bands at 2850–2950
ꢀ
1
ꢀ1
from C16TMABr) are also
and dC–H ca. 1470 cm
Fig. 4
extracted sample A2.
N
2
adsorption–desorption isotherm of the surfactant
observed. The latter are absent in the extracted material.
Moreover, the aromatic and C–F bands characteristic of the
fluoroaryl dangling groups are conserved in the extracted
material, demonstrating that the extraction is efficient at com-
pletely removing the surfactant without damaging the grafted
functions. This is confirmed by TGA–DTA measurements
(
4
> 95%) and the Q peak is more intense ( > 60%). These
results are in agreement with extensive condensation of the
silica walls. A condensation degree of about 90% was calcu-
lated. No T units corresponding to species issued from 1 could
be clearly observed. The disappearance of most of the fluorine
performed on as-synthesised and surfactant-extracted samples
ꢁ
28
(
which can be attributed to the elimination of the C16TMABr.
see ESI). TGA curves show a 53% mass loss before 400 C,
is due to the cleavage of the Si–Csp
be activated by the attractor inductive effect of fluorine
2
bond. Such cleavage might
ꢁ
A minor mass loss of 6% between 420 and 550 C is also
observed. Extracted samples display a mass loss of ca. 17%
2
7
atoms. This phenomenon occurs mainly during the material
formation and the surfactant extraction process, and appears
to be favoured by the presence of acid.
in this range, which coincides with an exothermic DTA peak
ꢁ
centred at 480 C. This decomposition step can be ascribed
to the fluoro-organic functions. Indeed, the TG mass loss in
this step is in agreement with the detected fluorine contents
for extracted C samples (5–6% Si–F/Sitotal , i.e. F/Si ꢂ 0.25–
Ordered mesoporous silica modified with
2
0
.3), confirming the higher incorporation of the fluoro-organic
-pentafluorophenylethyltriethoxysilane [PFPETES (2)]
group, and the absence of significant leaching of the organic
functions upon extraction.
The F MAS NMR spectrum of the surfactant-extracted
The XRD patterns recorded for sample C (functionalised with
precursor 2) before and after surfactant extraction show four
diffraction peaks in the 2y range 1–10 that can be indexed
as d100 , d110 , d200 and d210 and indicate a 2D-hexagonal sym-
19
ꢁ
sample C exhibited three lines at ꢀ148.6, ꢀ164.9 and ꢀ168.2
ppm that can be attributed to the aromatic fluorine nuclei in
metry (see Table 2 and ESI).z Sample C exhibits a MCM-41-
˚
type architecture with a unit cell parameter a of 43.3 A. High
resolution TEM imaging showed the presence of highly
ordered single domain ‘crystals’ of MCM-41 silica with a hex-
agonal lattice parameter from the Fourier transform filtered
˚
˚
image of a ¼ 34.6 A (d ¼ 30 A) (Fig. 7). The difference
1
00
between the d-values obtained by XRD and TEM can be
attributed to shrinking of the inorganic network during the
imaging process; in fact, the C samples are unstable under
the electron beam, due to the appreciable quantity of organic
material.
z Acidic media have also been used to obtain mesostructured silica
functionalised by precursor 2. Under the explored conditions, only a
worm-like ordering has been obtained, similar to those samples modi-
fied by 1. These poorly organised solids are not further discussed in this
paper.
29
Fig. 6
A2.
Si MAS NMR spectrum of the surfactant-extracted sample
New J. Chem., 2003, 27, 166–171
169

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29
Fig. 10 Si MAS NMR spectrum of the surfactant-extracted sample
C; the smooth line corresponds to the simulated spectrum.
Fig. 7 TEM micrographs of sample C (a) and the Fourier transform
FT) filtered image (b). The presence of channels (c) confirms a 2D
hexagonal mesostructure. Repeating distances of 30 A are calculated
from the Fourier transforms of the image.
(
˚
signals at 12.1 and 27.4 ppm were present and were assigned
to CH –CH –Si and CH –CH –Si of the ethyl spacer, respec-
2
2
2
2
tively. Two sharp lines were also observed at 16.1 and 58.5
ppm that can be assigned to the CH and CH2 of residual
3
2
ethoxy groups, respectively. Si MAS NMR spectroscopy
9
n
showed distinct resonances for siloxane (Q ¼ Si(OSi) -
n
m
(
(
OH)4ꢀn , n ¼ 2–4) and organosiloxane (T ¼ RSi(OSi)
m
-
OH)3 , m ¼ 1–3) centres, from TEOS and precursor 2, in
ꢀm
the surfactant-extracted material C (Fig. 10). A T/Q molar
ratio of 6/94 and a condensation degree of 84% for the silox-
ane network were calculated from the fit of the spectrum with
2
9
WINFIT software. The presence of residual ethoxy groups
reveals incomplete hydrolysis and condensation of precursor
2
which may explain the lower T/Q ratio in the surfactant-
extracted material compared to the initial T/Q molar ratio
of 10/90. However, this synthetic procedure allows grafting
of higher fluorophenyl contents than the precursor route start-
ing from precursor 1.
Fig. 8 FTIR spectra of a) pentafluorostyrene (PFS), b) sample C as-
prepared, c) sample C, extracted with acidic ethanol. Relevant C=C
and C–F vibrations are indicated.
Conclusion
Highly ordered fluorine-containing mesoporous siliceous
materials with MCM-41-type architecture were prepared for
the first time from co-condensation of TEOS and a fluoro-
organic precursor (1 or 2). For materials obtained using pre-
ortho, para and meta positions (Fig. 9). A much less intense
line was also observed at ꢀ175.5 ppm and was attributed to
1
3
the presence of an impurity. The C MAS NMR data confirm
the presence of aromatic carbons at 116.6, 136.5, 139.3, 144.1
and 146.8 ppm. The line at 116.6 ppm was assigned to the qua-
ternary carbon bonded to the ethyl spacer. From a spectral
simulation of 2 with ACD-Lab Software, the lines at 136.5,
cursor 1, the Si–Csp2 bonds were cleaved during the formation
and the surfactant extraction processes, leading to fluorine-
doped (i.e. F/Si < 0.06) MCM-41 silica materials. However,
a better choice of fluoro-organosilane (precursor 2) containing
an alkyl spacer between the pentafluorophenyl group and the
silicon centre allows one to preserve the organic functionality,
leading to ordered mesoporous MCM-41-type siliceous mate-
rials with higher fluorine contents (F/Si ꢂ 0.3).
139.3 and 144.1 were attributed to carbons in meta-, ortho-
and para-positions, respectively. Two weak and unresolved
Further investigations are in due course to improve the
fluorine loading, to evaluate the hydrophobic and fluorophilic
character of such materials for separation and adsorption
applications, and to shape these materials as transparent thin
films for optical devices.
Acknowledgements
The authors are grateful for funding from CNRS and Funda-
ci o´ n Antorchas; AM acknowledges participation in a student
project from ESCOM Cergy-Pontoise. GJAASI is a member
of CONICET.
19
Fig. 9
F MAS NMR spectrum of the surfactant-extracted sample C.
1
70
New J. Chem., 2003, 27, 166–171

View Article Online
1
6
Y. Lu, H. Fan, N. Doke, D. A. Loy, R. A. Assink, D. A. Lavan
and C. J. Brinker, J. Am. Chem. Soc., 2000, 122, 5258.
References
1
(a) J. S. Beck, J. C. Vartuli, W. J. Roth, M. E. Leonowicz, C. T.
17 (a) T. Asefa, M. J. Maclachlan, N. Coombs and G. A. Ozin, Nat-
ure, 1999, 402, 867; (b) S. Inagaki, G. Shiyou, T. Ohsuna and O.
Terasaki, Nature, 2002, 416, 304; (c) B. J. Melde, B. T. Holland,
C. F. Blanford and A. Stein, Chem. Mater., 1999, 11, 3302.
18 M. H. Lim and A. Stein, Chem. Mater., 1999, 11, 3285.
19 C. Sanchez and F. Ribot, New J. Chem., 1994, 18, 1007.
20 C. Roscher and M. Popall, Mater. Res. Soc. Symp. Proc., 1996,
435, 547.
Kresge, K. D. Schmitt, C. T.-W. Chu, D. H. Olson, E. W.
Sheppard, S. B. McCullen, J. B. Higgins and J. L. Schlenker,
J. Am. Chem. Soc., 1992, 114, 10 834. Recent reviews include
J. Y. Ying, C. Mehnert and M. S. Wong, Angew. Chem., Int.
Ed., 1999, 38, 57; (c) T. J. Barton, L. M. Bull, W. G. Klemperer,
D. A. Loy, B. McEnaney, M. Misono, P. A. Monson, G. Pez,
G. W. Scherer, J. C. Vartuli and O. M. Yaghi, Chem. Mater.,
1999, 11, 2633; (d ) G. J. A. A. Soler-Illia, C. Sanchez, B. Lebeau
and J. Patarin, Chem. Rev., 2002, 102, 4093.
K. Moller and T. Bein, Chem. Mater., 1998, 10, 2950.
A. Stein, B. J. Melde and R. C. Schroden, Adv. Mater., 2000, 12,
21 C. Zhang, F. Babonneau, C. Bonhomme, R. M. Laine, C. L.
Soles, H. A. Hristov and A. F. Yee, J. Am. Chem. Soc., 1998,
120, 8380.
22 S. A. Bagshaw, E. Prouzet and T. J. Pinnavaia, Science, 1995, 269,
1242.
2
3
1403–1419.
4
5
A. Sayari and S. Hamoudi, Chem. Mater., 2001, 13, 3151.
R. Burch, N. Cruise, D. Gleeson and S. C. Tsang, Chem.
Commun., 1996, 951.
T. Maschmeyer, F. Rey, G. Sankar and J. M. Thomas, Nature,
1995, 378, 159.
D. Brunel, A. Cauvel, F. Fajula and F. DiRenzo, Stud. Surf. Sci.
Catal., 1995, 97, 173.
D. Brunel, Microporous Mesoporous Mater., 1999, 27, 329.
D. Brunel, A. C. Blanc, A. Galarneau and F. Fajula, Catal.
Today, 2002, 73, 139.
23 (a) Q. Huo, D. I. Margolese, U. Ciesla, P. Feng, Thurman E.
Gier, P. Sieger, R. Leon, P. M. Petroff, F. Sch u¨ th and G. D.
Stucky, Nature, 1994, 368, 317; (b) Q. Huo, D. I. Margolese, U.
Ciesla, D. K. Demuth, P. Feng, T. E. Gier, P. Sieger, A. Firouzi,
B. F. Chmelka, F. Sch u¨ th and G. D. Stucky, Chem. Mater., 1994,
6, 1176.
24 H. Schmidt, H. Scholze and A. Kaiser, J. Non-Cryst. Solids, 1984,
63, 1.
25 C. E. Fowler, PhD Thesis, University of Bristol, UK, 2001.
26 G. Socrates, Infrared Characteristic Group Frequencies. Tables and
charts, Wiley, Chichester, 1994.
6
7
8
9
1
0
1
S. L. Burkett, S. D. Sims and S. Mann, Chem. Commun., 1996,
1
367.
C. E. Fowler, S. L. Burkett and S. Mann, Chem. Commun., 1997,
769.
27 (a) C. Eaborn, I. D. Jenkins and D. R. M. Walton, J. Chem. Soc.,
Perkin Trans. 2, 1974, 596; (b) C. Eaborn and K. C. Pande,
J. Chem. Soc., 1960, 1566.
1
1
1
1
2
3
D. J. MacQuarrie, Chem. Commun., 1996, 1961.
M. H. Lim, C. F. Blanford and A. Stein, J. Am. Chem. Soc., 1997,
28 M. T. J. Keene, R. D. M. Gougeon, R. Denoyel, R. K. Harris,
J. Rouquerol and P. L. Llewellyn, J. Mater. Chem., 1999, 9,
2843.
29 D. Massiot, F. Fayon, M. Capron, I. King, S. Le Calv e´ , B.
Alonso, J.-O. Durand, B. Bujoli, Z. Gan and G. Hoatson, Magn.
Res. Chem., 2002, 40, 70.
1
19, 4090.
F. Babonneau, L. Leite and S. Fontlupt, J. Mater. Chem., 1999,
, 175.
L. Mercier and T. J. Pinnavaia, Chem. Mater., 2000, 12, 188.
1
4
5
9
1
New J. Chem., 2003, 27, 166–171
171